The team has documented and discussed this several times. They have always recommend using service interfaces or HTTP calls inside your components if you intend on switching to client-side in the future.

Otherwise, for many apps, server-side Blazor works just fine. The component model is like any other frontend framework, not like Webforms at all, and by running server-side gives you a shorter path to the data and backend code you would normally put behind an API interface. This is an incredibly productivity boost.

If you don't need or want it, then don't use it, but it's a major leap forward.